refactor(css): add styles targeting SVG button/modal icons (#1464)

* refactor(css): add global classes for common icon types

* refactor(css): target child SVGs instead of creating new icon classes

* fix: fix ButtonWithDropdown style class spacing

src/components/PlexLoginButton/index.tsx

@@ -49,12 +49,14 @@ const PlexLoginButton: React.FC<PlexLoginButtonProps> = ({
         disabled={loading || isProcessing}
         className="plex-button"
       >
-        <LoginIcon className="w-5 h-5 mr-1" />
-        {loading
-          ? intl.formatMessage(globalMessages.loading)
-          : isProcessing
-          ? intl.formatMessage(messages.signingin)
-          : intl.formatMessage(messages.signinwithplex)}
+        <LoginIcon />
+        <span>
+          {loading
+            ? intl.formatMessage(globalMessages.loading)
+            : isProcessing
+            ? intl.formatMessage(messages.signingin)
+            : intl.formatMessage(messages.signinwithplex)}
+        </span>
       </button>
     </span>
   );